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Magnetic Nature of Light Transmission through a 5-nm Gap

TitleMagnetic Nature of Light Transmission through a 5-nm Gap
Publication TypeJournal Article
Year of Publication2018
AuthorsYang, H, Kim, DS, Kim, R, Ahn, JS, Kang, T, Jeong, J, Lee, D
JournalScientific Reports
Date Published02
Type of ArticleArticle
ISBN Number2045-2322
Accession NumberWOS:000424634000005
Keywordsantenna, metal, plasmonics, Technology - Other Topics, terahertz field enhancement

Slot antennas have been exploited as important building blocks of optical magnetism because their radiations are invoked by the magnetic fields along the axes, as vectorial Babinet principle predicts. However, optical magnetism of a few-nanometer-width slit, for which fascinating applications are found due to the colossal field enhancement but Babinet principle fails due to the nonnegligible thickness, has not been investigated. In this paper, we demonstrated that the magnetic field plays a dominant role in light transmission through a 5-nm slit on a 150-nm-thick gold film. The 5-nm slit was fabricated by atomic layer lithography, and the transmission was investigated for various incident angles by experiment and simulation at 785-nm wavelength. We found that, due to the deep subwavelength gap width, the transmission has the same incident angle dependence as the tangential magnetic field on the metal surface and this magnetic nature of a nanogap holds up to similar to 100-nm width. Our analysis establishes conditions for nanogap optical magnetism and suggests new possibilities in realizing magnetic-field-driven optical nonlinearities.

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